Why we should be especially impressed by Jannik Sinner's ATP Finals win over Holger Rune

When Jannik Sinner clinched his 6-2, 5-7, 6-4 win over Holger Rune in Turin on Thursday night, he raised his index finger over his head, in the gesture that commonly means, “I’m No. 1.”

Is that what the 22-year-old was trying to say? If so, what he is No. 1 of? The Green group in Turin? It’s true, Sinner did finish the round-robin 3-0, and he’ll advance to the semifinals this weekend in the top spot from his section. Which is great, but I’m not sure it’s something to raise your index finger about. Maybe Sinner has bigger things on his mind. After the season and the week he’s had, the No. 1 ranking is looking like something that may just be in his future.

Sinner has been winning a lot of late, but there are a few reasons to be especially impressed with his victory over Rune. First, it came two days after his first win over Novak Djokovic; a letdown may have been expected, but none was in evidence. Second, he had already qualified for the semifinals, whether he prevailed or not. Third, he was 0-2 against Rune, who needed to win this match to move on.

Sinner also appeared to be suffering from back pain in the middle of the match, and in the final set he found himself serving at 3-4, down break point. Even the packed Turin crowd, which cheered and sang for him for all two and a half hours of this match, would have understood if he had packed it in and kept his powder dry for the weekend.

But Sinner wasn’t going to do that. This consummate young professional has standards he wants to set for himself for the future.

“Resetting after the good win over Novak was important,” he said.

“I had never beaten him either,” he added of Rune, a player who will surely be a major rival of his in the years ahead.

Rather than a post-Djokovic letdown, Sinner rode the momentum from that win through the first set and a half against Rune. He started by out-gunning him from the baseline; Rune simply couldn’t catch up to Sinner’s pace early on. Later the first set, Rune tried barging his way to net, but that didn’t work either; Sinner was pinpoint with his passing shots. He won the first set in 32 minutes.

Rune’s only hope was that Sinner would come down off his mountaintop. At 4-4 in the second, he did. First, he began to clutch his back. Then he began to misfire. Serving at 5-6, Sinner made three errors, and Rune broke with a nicely measured pass-lob combination for the set.

Despite that fall off, Sinner never asked for the trainer or took an extended break. In the third set, his back issue seemed to clear, and he returned to controlling the action. At 1-1, he had two break points in a 13-minute Rune service game. At 2-2, Sinner had another break point. After saving one on his own serve at 3-4, Sinner finally broke through with a brilliant forehand approach and low-volley winner that left Rune staring across the net in disbelief. From there, Sinner held for this perhaps-unnecessary but still-satisfying win.

Sinner hit 36 winners and made 10 errors, and was 20 of 23 at net. He’ll go into the semifinals as the event’s hottest player and the obvious fan favorite. Will he be holding his index finger high after the final on Sunday afternoon?